Start by preparing the brownies. Use the directions on the box to prepare the batter. The pour the batter onto a large baking sheet (around 16 x 11 inches) that is covered with parchment paper. Spread the batter evenly on the baking sheet.

Bake at 350 for 10-15 minutes, until a toothpick inserted into the middle comes out clean. Let the brownies cool in the pan.

While the brownies are cooling, prepare the caramel. Melt the butter in a saucepan over medium heat. Whisk in the butter. Once the butter has melted, add the half and half, vanilla, and salt. Whisk together, and let the mixture bubble, stirring frequently for 5-7 minutes, until thick.

Pour the warm caramel over the brownies, and use a spatula to spread it our evenly. Let cool for 5 minutes.

Use the parchment to pull the brownies out of the pan. Cut the brownies in half. Then cut one of those halves horizontally twice, creating three long thin pieces. Then cut those pieces into 4 rectangular pieces. These are the top halves of the sandwiches. Then cut the other half of the brownies horizontally to create three long thin pieces. Spread ice cream over these pieces of brownie. Then arrange the tops of the sandwiches over, caramel side facing down. Use a sharp knife to cut through the sandwiches. Repeat assembling more sandwiches. Then immediately place in the fridge to chill.